how to reduce the mains voltage

On 2020-07-14 09:12, Bill Gill wrote:
> On 7/14/2020 8:07 AM, Phil Hobbs wrote:
>> On 2020-07-14 07:04, default wrote:
>>> On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:
>>>
>>>> Your bill went up because of light bulbs and shit with heating 
>>>> elements, maybe the microwave if you use it alot, and of course if 
>>>> you have an electric stove.
>>>>
>>>> Those types of motors usually run more efficiently on slightly 
>>>> higher voltage. Voltage up, current is the same or lower. Well power 
>>>> actually, it might be the same current but the phase changes the 
>>>> power factor. You pay by the watt, not the amp.
>>>
>>>
>>> I think you are mistaken.
>>>
>>> Some years ago I put a voltage stabilizer on a large fan.  (adjustable
>>> AC voltage regulator intended to be used for large motors) As I
>>> adjusted the voltage lower the current dropped linearly until it
>>> reached about 95 VAC then started rising exponentially as I dropped it
>>> lower.
>>>
>>> Torque of the motor may be dependent on voltage, but the torque
>>> required for a refrigeration compressor varies with time.  Starting up
>>> with the system equilibrated, there's little back-pressure on the
>>> compressor so it is lightly loaded, as back pressure builds the torque
>>> necessary to maintain synchronous speed increases.
>> <snip>
>>
>> But if you have a momentary power dropout, it has to restart into the 
>> full back-pressure of the evaporator.&nbsp; If the A/C isn't a tiny one, I 
>> sure wouldn't be mickey-mousing anything that would increase the mains 
>> impedance.
>>
>> Electrical codes contain a lot of non-obvious and very expensive wisdom.
>>
>> Cheers
>>
>> Phil Hobbs
>>
>>
>>
>>
> My central AC won't restart immediately after a dropout.&nbsp; It has
> a delay time to allow the pressure to drop.
> 
> Bill

That's certainly comforting, but isn't universal, at least in smaller 
units.  The thing I'd be worried about is a short-that-isnt-a-short--as 
in a shorted rectifier in an old-time transformer/rectifier/filter 
supply.  The current isn't enough to blow the mains breaker but is quite 
sufficient to make the transformer catch fire.

I lost a very nice Krohn-Hite dual channel filter that way--a 'computer 
grade' capacitor's clamp had gotten loose over the years, and it slipped 
down and shorted out to the box, resulting in clouds of transformer 
smoke.  It was a good thing that I was in the lab at the time.  Didn't 
even blow the fuse in the unit.  (A bit of fish paper would have been a 
nice touch.)

When nobody's around, we keep everything turned off at the power bar to 
prevent that sort of thing--industrial-type Tripplites, natch.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Tue, 14 Jul 2020 09:07:33 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 2020-07-14 07:04, default wrote:
>> On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:
>> 
>>> Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.
>>>
>>> Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.
>> 
>> 
>> I think you are mistaken.
>> 
>> Some years ago I put a voltage stabilizer on a large fan.  (adjustable
>> AC voltage regulator intended to be used for large motors) As I
>> adjusted the voltage lower the current dropped linearly until it
>> reached about 95 VAC then started rising exponentially as I dropped it
>> lower.
>> 
>> Torque of the motor may be dependent on voltage, but the torque
>> required for a refrigeration compressor varies with time.  Starting up
>> with the system equilibrated, there's little back-pressure on the
>> compressor so it is lightly loaded, as back pressure builds the torque
>> necessary to maintain synchronous speed increases.
><snip>
>
>But if you have a momentary power dropout, it has to restart into the 
>full back-pressure of the evaporator.  If the A/C isn't a tiny one, I 
>sure wouldn't be mickey-mousing anything that would increase the mains 
>impedance.
>
>Electrical codes contain a lot of non-obvious and very expensive wisdom.
>
>Cheers
>
>Phil Hobbs

You are correct - This controller has a built in time delay and won't
allow me to turn the compressor on and off at will.  Commercial
(large) AC's monitor the back pressure before allowing the compressors
to run, and even cheap consumer products like refrigerators have an
"overload relay" that over heats (because the compressor motor is
stalled and eating a lot of amps) then the bi-metallic relay cools off
and eventually gives it another go.

On Tue, 14 Jul 2020 10:18:35 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 2020-07-14 09:12, Bill Gill wrote:
>> On 7/14/2020 8:07 AM, Phil Hobbs wrote:
>>> On 2020-07-14 07:04, default wrote:
>>>> On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:
>>>>
>>>>> Your bill went up because of light bulbs and shit with heating 
>>>>> elements, maybe the microwave if you use it alot, and of course if 
>>>>> you have an electric stove.
>>>>>
>>>>> Those types of motors usually run more efficiently on slightly 
>>>>> higher voltage. Voltage up, current is the same or lower. Well power 
>>>>> actually, it might be the same current but the phase changes the 
>>>>> power factor. You pay by the watt, not the amp.
>>>>
>>>>
>>>> I think you are mistaken.
>>>>
>>>> Some years ago I put a voltage stabilizer on a large fan.&#4294967295; (adjustable
>>>> AC voltage regulator intended to be used for large motors) As I
>>>> adjusted the voltage lower the current dropped linearly until it
>>>> reached about 95 VAC then started rising exponentially as I dropped it
>>>> lower.
>>>>
>>>> Torque of the motor may be dependent on voltage, but the torque
>>>> required for a refrigeration compressor varies with time.&#4294967295; Starting up
>>>> with the system equilibrated, there's little back-pressure on the
>>>> compressor so it is lightly loaded, as back pressure builds the torque
>>>> necessary to maintain synchronous speed increases.
>>> <snip>
>>>
>>> But if you have a momentary power dropout, it has to restart into the 
>>> full back-pressure of the evaporator.&#4294967295; If the A/C isn't a tiny one, I 
>>> sure wouldn't be mickey-mousing anything that would increase the mains 
>>> impedance.
>>>
>>> Electrical codes contain a lot of non-obvious and very expensive wisdom.
>>>
>>> Cheers
>>>
>>> Phil Hobbs
>>>
>>>
>>>
>>>
>> My central AC won't restart immediately after a dropout.&#4294967295; It has
>> a delay time to allow the pressure to drop.
>> 
>> Bill
>
>That's certainly comforting, but isn't universal, at least in smaller 
>units.  The thing I'd be worried about is a short-that-isnt-a-short--as 
>in a shorted rectifier in an old-time transformer/rectifier/filter 
>supply.  The current isn't enough to blow the mains breaker but is quite 
>sufficient to make the transformer catch fire.
>
>I lost a very nice Krohn-Hite dual channel filter that way--a 'computer 
>grade' capacitor's clamp had gotten loose over the years, and it slipped 
>down and shorted out to the box, resulting in clouds of transformer 
>smoke.  It was a good thing that I was in the lab at the time.  Didn't 
>even blow the fuse in the unit.  (A bit of fish paper would have been a 
>nice touch.)
>
>When nobody's around, we keep everything turned off at the power bar to 
>prevent that sort of thing--industrial-type Tripplites, natch.
>
>Cheers
>
>Phil Hobbs

I have a wall-switch that disconnects the mains from the AC outlet.  I
don't trust leaving it on and unattended when I'm away.

I am curious about how they do the time delay though....  If the AC
power has been off for a time (several minutes) and I apply power the
compressor will run right away.  Yet if I switch the mains off and on
quickly it goes into it's time delay.

I figure that they must be looking at the charge on a cap that
gradually bleeds off when power is removed - and prevents a re-start
and goes into it's timing cycle instead.  Easy to implement with a
micro controller chip...

On Mon, 13 Jul 2020 23:12:03 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Monday, July 13, 2020 at 8:31:34 AM UTC-7, default wrote:
>> I have an older window air conditioner that I'd like to hang on to for
>> a few more years.  The name plate says it is 220 VAC and since the
>> power company went through and upgraded the distribution network and
>> replaced HT and transformers my service which had been running 210-220
>> volts is now a steady 250 volts and my bill is up ~15%.
>...
>
>> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
>> power transformer, wired to buck the voltage makes any sense?
>
>It doesn't make much sense to me; ask, instead, the power company to 
>adjust the line voltage to an acceptable value.   The taps in their
>transmission line drops are the solution to many such problems, if
>they know that you have found an excessive voltage.   I'm not sure
>250V average is excessive, but if there are peaks and dips...
I called my power company to complain about the high voltage and they
said it was within spec. The voltage at my place is 250 minimum with
occasional spikes to 260. The spikes are transient but long enough in
duration to be read with a digital voltmeter. And long enough for the
CNC lathe's spindle drive to alarm out.
Eric

On Tue, 14 Jul 2020 09:04:53 -0700, etpm@whidbey.com wrote:

>On Mon, 13 Jul 2020 23:12:03 -0700 (PDT), whit3rd <whit3rd@gmail.com>
>wrote:
>
>>On Monday, July 13, 2020 at 8:31:34 AM UTC-7, default wrote:
>>> I have an older window air conditioner that I'd like to hang on to for
>>> a few more years.  The name plate says it is 220 VAC and since the
>>> power company went through and upgraded the distribution network and
>>> replaced HT and transformers my service which had been running 210-220
>>> volts is now a steady 250 volts and my bill is up ~15%.
>>...
>>
>>> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
>>> power transformer, wired to buck the voltage makes any sense?
>>
>>It doesn't make much sense to me; ask, instead, the power company to 
>>adjust the line voltage to an acceptable value.   The taps in their
>>transmission line drops are the solution to many such problems, if
>>they know that you have found an excessive voltage.   I'm not sure
>>250V average is excessive, but if there are peaks and dips...
>I called my power company to complain about the high voltage and they
>said it was within spec. The voltage at my place is 250 minimum with
>occasional spikes to 260. The spikes are transient but long enough in
>duration to be read with a digital voltmeter. And long enough for the
>CNC lathe's spindle drive to alarm out.
>Eric

It is within spec at 250. (if only just)

Remember when it was 110/220 volts nominal?  I suspect as time goes on
it will creep up.  Most recent equipment is sophisticated enough to
adapt.  I'm impressed by how consistent it is since their upgrade.
There are three houses that share one transformer, and the lowest I've
seen it is 247 and highest is 252, but most days it is spot-on 250.

My house and the others on this tranny are at the end of the HT line
for this street.

In article <qkuogfda30qbsoghmqghsoe62b7qnnkirl@4ax.com>, 
default@defaulter.net says...
> 
> I have an older window air conditioner that I'd like to hang on to for
> a few more years.  The name plate says it is 220 VAC and since the
> power company went through and upgraded the distribution network and
> replaced HT and transformers my service which had been running 210-220
> volts is now a steady 250 volts and my bill is up ~15%.
> 
> The increased consumption is tied to how much I run the AC and since
> the upgrade I've already had to replace both the compressor and fan
> motor run caps.  The compressor one died a quiet death, and the fan
> cap melted and smoked. The compressor cap went out the week they
> changed the transformer and the fan cap about a month later. I put in
> higher voltage ones and the AC is back on line.
> 
> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
> power transformer, wired to buck the voltage makes any sense?  

i Would sayt you need to get them back out there and move a Tap on the 
service transformer..

 The voltage is too high..

On 14/07/2020 8:08 am, etpm@whidbey.com wrote:
> On Mon, 13 Jul 2020 11:31:30 -0400, default <default@defaulter.net>
> wrote:
> 
>> I have an older window air conditioner that I'd like to hang on to for
>> a few more years.  The name plate says it is 220 VAC and since the
>> power company went through and upgraded the distribution network and
>> replaced HT and transformers my service which had been running 210-220
>> volts is now a steady 250 volts and my bill is up ~15%.
>>
>> The increased consumption is tied to how much I run the AC and since
>> the upgrade I've already had to replace both the compressor and fan
>> motor run caps.  The compressor one died a quiet death, and the fan
>> cap melted and smoked. The compressor cap went out the week they
>> changed the transformer and the fan cap about a month later. I put in
>> higher voltage ones and the AC is back on line.
>>
>> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
>> power transformer, wired to buck the voltage makes any sense?
>    Where I live we get 250 volts pretty steadily. In my shop are
> several CNC machines, one of which cannot easily tolerate the 250
> volts. So I use two buck/boost xmfrs wired in a particular buck
> configuration to lower the 3 phase voltage going to that one machine.
> Since doing so the machine has not once alarmede out due to over
> voltage.
>     I also wired up a little 120 to 12 volt xmfr in buck configuration
> to lower the 125 volts from the outlet to the 110 volts needed for a
> tube amp.
>    There are directions online on how to select the proper sized xmfr
> for the load it will be seeing and how to wire the thing in buck
> configuration.
> Eric
> 

Eric could you please give me directions to on-line info? I'm looking at dropping the voltage to a 
transformer so that I get lower secondaries out of it inexpensively. Single phase. My Google Fu 
isn't very strong on this one. I remember Big Clive doing similar in one of his videos a while back 
but have been unable to find that again.

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy little classification 
in the DSM"
David Melville

This is not an email and hasn't been checked for viruses by any half-arsed self-promoting software.

On Tue, 11 Aug 2020 22:01:39 +1200, ~misfit~
<shaun.at.pukekohe@gmail.com> wrote:

>On 14/07/2020 8:08 am, etpm@whidbey.com wrote:
>> On Mon, 13 Jul 2020 11:31:30 -0400, default <default@defaulter.net>
>> wrote:
>> 
>>> I have an older window air conditioner that I'd like to hang on to for
>>> a few more years.  The name plate says it is 220 VAC and since the
>>> power company went through and upgraded the distribution network and
>>> replaced HT and transformers my service which had been running 210-220
>>> volts is now a steady 250 volts and my bill is up ~15%.
>>>
>>> The increased consumption is tied to how much I run the AC and since
>>> the upgrade I've already had to replace both the compressor and fan
>>> motor run caps.  The compressor one died a quiet death, and the fan
>>> cap melted and smoked. The compressor cap went out the week they
>>> changed the transformer and the fan cap about a month later. I put in
>>> higher voltage ones and the AC is back on line.
>>>
>>> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
>>> power transformer, wired to buck the voltage makes any sense?
>>    Where I live we get 250 volts pretty steadily. In my shop are
>> several CNC machines, one of which cannot easily tolerate the 250
>> volts. So I use two buck/boost xmfrs wired in a particular buck
>> configuration to lower the 3 phase voltage going to that one machine.
>> Since doing so the machine has not once alarmede out due to over
>> voltage.
>>     I also wired up a little 120 to 12 volt xmfr in buck configuration
>> to lower the 125 volts from the outlet to the 110 volts needed for a
>> tube amp.
>>    There are directions online on how to select the proper sized xmfr
>> for the load it will be seeing and how to wire the thing in buck
>> configuration.
>> Eric
>> 
>
>Eric could you please give me directions to on-line info? I'm looking at dropping the voltage to a 
>transformer so that I get lower secondaries out of it inexpensively. Single phase. My Google Fu 
>isn't very strong on this one. I remember Big Clive doing similar in one of his videos a while back 
>but have been unable to find that again.
>
>Cheers,
http://www.afcaforum.com/attachment.php?id=40251

On Tue, 11 Aug 2020 22:01:39 +1200, ~misfit~
<shaun.at.pukekohe@gmail.com> wrote:

>On 14/07/2020 8:08 am, etpm@whidbey.com wrote:
>> On Mon, 13 Jul 2020 11:31:30 -0400, default <default@defaulter.net>
>> wrote:
>> 
>>> I have an older window air conditioner that I'd like to hang on to for
>>> a few more years.  The name plate says it is 220 VAC and since the
>>> power company went through and upgraded the distribution network and
>>> replaced HT and transformers my service which had been running 210-220
>>> volts is now a steady 250 volts and my bill is up ~15%.
>>>
>>> The increased consumption is tied to how much I run the AC and since
>>> the upgrade I've already had to replace both the compressor and fan
>>> motor run caps.  The compressor one died a quiet death, and the fan
>>> cap melted and smoked. The compressor cap went out the week they
>>> changed the transformer and the fan cap about a month later. I put in
>>> higher voltage ones and the AC is back on line.
>>>
>>> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
>>> power transformer, wired to buck the voltage makes any sense?
>>    Where I live we get 250 volts pretty steadily. In my shop are
>> several CNC machines, one of which cannot easily tolerate the 250
>> volts. So I use two buck/boost xmfrs wired in a particular buck
>> configuration to lower the 3 phase voltage going to that one machine.
>> Since doing so the machine has not once alarmede out due to over
>> voltage.
>>     I also wired up a little 120 to 12 volt xmfr in buck configuration
>> to lower the 125 volts from the outlet to the 110 volts needed for a
>> tube amp.
>>    There are directions online on how to select the proper sized xmfr
>> for the load it will be seeing and how to wire the thing in buck
>> configuration.
>> Eric
>> 
>
>Eric could you please give me directions to on-line info? I'm looking at dropping the voltage to a 
>transformer so that I get lower secondaries out of it inexpensively. Single phase. My Google Fu 
>isn't very strong on this one. I remember Big Clive doing similar in one of his videos a while back 
>but have been unable to find that again.
>
>Cheers,
Search for buck/boost transformer. Here's a link:
https://www.federalpacific.com/tools/buck-boost-transformer-calculator-selector/
Search youtube too, there are lots of videos expalining them.
Eric

On Tue, 11 Aug 2020 22:01:39 +1200, ~misfit~
<shaun.at.pukekohe@gmail.com> wrote:

>On 14/07/2020 8:08 am, etpm@whidbey.com wrote:
>> On Mon, 13 Jul 2020 11:31:30 -0400, default <default@defaulter.net>
>> wrote:
>> 
>>> I have an older window air conditioner that I'd like to hang on to for
>>> a few more years.  The name plate says it is 220 VAC and since the
>>> power company went through and upgraded the distribution network and
>>> replaced HT and transformers my service which had been running 210-220
>>> volts is now a steady 250 volts and my bill is up ~15%.
>>>
>>> The increased consumption is tied to how much I run the AC and since
>>> the upgrade I've already had to replace both the compressor and fan
>>> motor run caps.  The compressor one died a quiet death, and the fan
>>> cap melted and smoked. The compressor cap went out the week they
>>> changed the transformer and the fan cap about a month later. I put in
>>> higher voltage ones and the AC is back on line.
>>>
>>> I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
>>> power transformer, wired to buck the voltage makes any sense?
>>    Where I live we get 250 volts pretty steadily. In my shop are
>> several CNC machines, one of which cannot easily tolerate the 250
>> volts. So I use two buck/boost xmfrs wired in a particular buck
>> configuration to lower the 3 phase voltage going to that one machine.
>> Since doing so the machine has not once alarmede out due to over
>> voltage.
>>     I also wired up a little 120 to 12 volt xmfr in buck configuration
>> to lower the 125 volts from the outlet to the 110 volts needed for a
>> tube amp.
>>    There are directions online on how to select the proper sized xmfr
>> for the load it will be seeing and how to wire the thing in buck
>> configuration.
>> Eric
>> 
>
>Eric could you please give me directions to on-line info? I'm looking at dropping the voltage to a 
>transformer so that I get lower secondaries out of it inexpensively. Single phase. My Google Fu 
>isn't very strong on this one. I remember Big Clive doing similar in one of his videos a while back 
>but have been unable to find that again.
>
>Cheers,

See:
https://sound-au.com/articles/buck-xfmr.htm#s30

Explains "the proper way" to wire a buck boost.  Both of the methods
shown work, one is just slightly more efficient.

My AC uses 7-8 amps so my 24 VCT transformer is rated at 10 amps or
240 VA.